This invention relates generally to reactors for producing gases containing carbon monoxide and hydrogen by means of partial oxidation of finely subdivided solid or liquid fuels, particularly high ash fuels, the partial oxidation process taking place at high temperatures and increased pressure in an atmosphere of a carburation fluid containing free oxygen.
In producing gases from powdery or liquid fuel by means of partial oxidation, the fuel reacts in flame reaction with the oxygen containing carburation fluid. Dependent on the type of the fuel and on the application of the gas, the final temperatures of the reaction are between 1,200.degree. and 1,600.degree. C. whereas the flame itself can reach temperatures over 2,000.degree. C. In the case when high ash fuels are employed, the mineral residues during the partial oxidation process are brought into a molten condition.
The flame reaction takes place in a refractory reaction chamber having as a rule a rotation-symmetrical shape whereby known-gas producing methods differ from one another by the arrangement of the burners and by the mode of discharge of the generated hot crude gas and of the molten slag. Such known gas generating processes of the aforedescribed type are frequently performed under an increased pressure, such as, for example, 3 MPA. Known reactors for such pressure processes consist for example of an outer pressure vessel in the interior of which the actual reaction chamber takes place. The shape of the reaction chamber is determined by its walls which include water-cooled pipes. The tubular walls at the sides adverse to the flame are covered with a layer of a refractory tamping or tamped mass, such as for example, on the basis of silicium carbide. The adherence of the temping mass to the cooling pipes is insured by holding pins having a diameter of 10 millimeters, for example, and a length of 10 millimeters. The holding pins are secured to the upper surface of the pipes by welding and project into the layer of the tamping mass. The thickness of the refractory later is adjusted such that its upper surface temperature is lower than the solidification temperature of the molten slag produced during the process of the partial oxidation. Accordingly, during the operation of the reactor an additional layer of solidified slag is formed on the upper surface of the tamping mass with solid layer changing gradually into a pasty zone and finally into a liquid slag film which continuously flows off. The cooling of the tubular wall can be effected by a pressurized water having a temperature below the boiling point or at the boiling point.
The purpose of the tubular wall is to reliably protect the outer pressure jacket against overheating due to radiation and convection heat flows. A thermally insulating multiple layer of refractory material is therefore provided between the tubular wall and the outer pressure jacket. Due to expansion joints in the brick lining and due to unavoidable fissures and the porosity of the refractory material, this multiple insulating layer has unavoidably a considerably and locally unpredictable permeability to the gas. As a consequence, when the reactor as usual is ignited at an approximately atmospheric pressure and when brought to a hot condition and subject to the full operational pressure, the rapid pressure increase may cause leakage currents to such an extent that the pressure jacket may become locally overheated. The same danger may take place when due to high output or due to a partial clogging by slag increased pressure differences within the reaction chamber and in the discharge channel for the crude gas are generated.
As a rule, it is possible to operate the cooled tubular wall at temperatures above the steam condensation point while the temperature of the pressure jacket remains under this condensation point. Nevertheless the gas permeability of the insulating layer results in a condensation of steam on the pressure jacket and contributes to its corrosion.
It has been devised to rinse the refractory layer or the joints in the refractory layer by an inert gas. The gas permeability of the refractory layer which cannot be at least for a period of time localized diminishes however even at large quantities of rinsing inert gas the effect of the proposed measure. Embodiments of reactors having cooled tubular wall structures are known in which the individual pipes are arranged side-by-side and interconnected by welded webs extending over the entire length of the cooling pipes. In this manner the tubular wall becomes gas-tight. The communication between the reaction chamber and the interspace between the tubular wall and the pressure jacket which is necessary for the pressure equalization is limited to one or more controllable openings rinsed by an inert gas.
This prior art solution results in very solid construction of the tubular wall having an additional advantage in a simple mounting structure and easy assembly. The rigidity of the tubular wall on the other hand has the following disadvantages:
During the start and the termination of the operation and in the case of change of the load it cannot be avoided that the tamping mass and the solidifed slag either expand or contract. The rigidly welded tubular wall structure, however, cannot accommodate itself to such length variation and consequently displacement of the tamping mass from the tubular wall frequently takes place. The exposed parts of the cooling pipes or of the jackets due to the displacement of the refractory mass are subject to multiple thermal load which in turn may cause an endangerment of the reactor due to local overheating.